AND ITS BIGGEST LIMITATION IS A MASSIVE BENEFIT:

At the upper school construction site, Ms Airaksinen's team are busy slicing up slabs of engineered wood called CLT (cross-laminated timber) which is produced by bonding together layers of wooden panels at right angles. "You're making the wood stiffer, so that makes the wood much stronger," she explains.

Engineered wood like CLT has a range of environmental benefits, including being much lighter than many building materials, so less heavy machinery and energy is needed during construction. Buildings can also be quicker to complete since there is no drying phase as there is with concrete.

Plus, wooden buildings actually remove more carbon dioxide from the atmosphere than they emit; they can hold in carbon that is absorbed from the atmosphere by trees for five to six decades. By contrast, steel and concrete leave massive carbon footprints.

"It can really help us with climate change," says Ali Amiri, a sustainable buildings researcher at Aalto University near Helsinki, and a former civil engineer.

"If we go through the comparison with wooden buildings and other buildings like concrete or steel or even brick buildings, [wood has] something like 20 to even 30% lower greenhouse gas emissions. So this is very good news."

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